1. Field of the Invention
This invention concerns a semiconductor optoelectronic component consisting of a ribbon-shaped waveguide that is curved more than two degrees with inwardly sloping sides.
2. Description of the Related Art
The type of optoelectronic component in the present invention is illustrated in FIG. 1. In this figure, component 10 includes a substrate 12 and an approximately rectangular parallelpiped ribbon-shaped waveguide 14. When the component is formed by joining a laser and a modulator, the length of the ribbon waveguide is typically 600 microns and its width is 2.5 microns. The waveguide includes lateral sides 16 and 18. The substrate and the waveguide are formed by stacking layers of semiconductor material. The two ends of the stack are covered by a metallic layer that provides electric contact. Reduced to its simplest form, the stack is formed by a first layer (the substrate), by a vertical optical confinement layer (in direction Oyo) for waves propagating in the guide, by a lateral optical confinement layer (in direction Ox) and by a contact layer. This last layer is thin compared to the thickness of the lateral optical confinement layer, which constitutes in fact the semiconductor channel in which the waves are propagated. Classically, two improvements have been separately made to this component. On the one hand, the rectangular shape of the ribbon guide has been curved to prevent interference from waves reflecting on the output face of the component (and also possibly on the entry face). This curvature has been obtained by chemical etching with hydrochloric acid during manufacture of the component. On the other hand, the lateral sides of the ribbon guide have been sloped inward in relation to the vertical of the substrate in order to reduce the electrical resistance of the component. Moreover, for this same component a very slight curvature of the guide, at most of two degrees, has been created. The slope of the lateral sides and the very slight curvature were obtained by chemical attack with hydrobromic acid. These features will be developed later in the presentation of the invention.
However, using these techniques it is not possible to obtain a curvature of the guide ribbon greater than two degrees and a slope of the lateral sides for the same component. Chemical attack by hydrochloric acid allows obtaining the curvature of the guide, but not the slope of the sides and attack by bromohydric acid allows obtaining the slope of the sides, but not a curvature of the waveguide of greater than two degrees.